Recording instrument



March 28, 1939.

' INVE OR. JA MES D. CUNNINGHAM TIZCWQM A'ITORNEY5 Patented Mar. 28, 1939 UNITED STATES PATENT OFFICE RECORDING INSTRUlVIENT James D. Cunningham, Chicago, 111., assignor to Republic Flow Meters Company, Chicago, 111., a corporation of Illinois 1 Claim.

This invention relates to recording instruments, and is illustrated as embodied in such an instrument having a pen which automatically draws a record on a rotating chart.

An object of the invention is to simplify the insertion and removal of the charts from the instrument, and to insure that without special attention being paid to its adjustment a new chart when inserted will always be in the same time position as the one just removed.

I utilize, in the embodiment illustrated, a chart having a central opening which seats over a driving post forming part of the instrument, and an offset timing opening seating over a timing pin or the like and which is arranged in a definite position relative to the indicia printed on the chart.

An important feature of the invention relates to holding the chart in position by a yielding member formed with an opening for the driving post and providing an annular clamping portion engaging and holding the chart about the post. Preferably this member is arranged to serve the additional function of a pen lifter.

The above and other objects and features or the invention, including various novel combinations of parts and desirable particular arrangements, will be apparent from the following description of the illustrative embodiment shown in the accompanying drawing, in which:

Figure 1 is a plan view of a recording instrument embodying the invention;

Figure 2 is a partial section therethrough; and

Figure 3 is a partial plan view of the chart used therewith.

The illustrated chart I I0 is formed with printed indicia, such as a series of concentric circles I2 arranged on a suitable scale to indicate temperature, pressure, or other condition whose value is to be recorded on the chart, and a series of arcuate time lines I4 on the arcs of circles whose centers are outside the periphery of the chart and which pass through the center of the chart. The time lines I4 at different hours of the day successively coincide with the path of movement of a recording pen I6 pivoted adjacent the periphery of the chart and actuated by any of the well-known condition-measuring devices (not herein shown).

The chart is intended for use with an instrument shown as including a clock mechanism inclosed in a suitable housing 22 formed with an opening in its upper face, and the final gear 24 of which is frictionally mounted on, and adjustable relative to, .a driving post 26 having a flange 28 in the opening 20 and supporting the central portion of the chart IIO when mounted in the instrument. The part I26 of the driving post 26 which is above the flange 28 fits into an opening I40 in the center of the chart. The chart also has an opening I50, arranged in .a predetermined definite relation with respect to the indicia I2 and I4 printed on the chart, and which fits over a timing pin I30 carried by the flange 28.

The chart is held clamped in place by a washer or the like 60 which encircles the part I26 of the driving post, and which is secured to the lower face of an annular end portion 62 of an arm I36, shown as a leaf spring secured at its outer end to the instrument casing. The inner end of the arm I36 is turned up, to be grasped conveniently by an operator when changing charts, and to clear the timing pin I30. The thickness of the washer 60 is such that the pin I30 is also cleared by the body of arm I36 on the other side of the driving post I26.

The arm I36 preferably carries a lateral projection 38 extending beneath the pen I6, so that lifting the arm I36 to release the chart also serves to lift the pen l6 off the chart.

While one illustrative arrangement has been described in detail, it is not my intention to limit the scope of my invention to that particular arrangement, or otherwise than by the terms of the appended claim. The present application is a division of my application No. 57,657, filed January 6, 1936, now Patent No. 2,073,143.

I claim:

An instrument comprising a driving post provided with a flange for supporting a chart having an opening to be centered on said post and yielding holding means for the chart including a leaf spring arm secured at one end to the instrument beyond the margin of the chart and biased toward the chart, said holding means being formed with an annular portion loosely encircling the driving post and directly engaging the chart to press it against the supporting flange.

JAMES D. CUNNINGHAM. 

